A snapshot of current genetic testing practice in Lynch syndrome: The results of a representative survey of 33 Latin American existing centres/registries.

We aimed to assess the current genetics practice to manage patients with Lynch syndrome (LS) across Latin America. A Latin American LS survey was sent out to 52 centres/registries, comprising a total of 12 countries from the region. Overall, 33 centres completed the survey, of which the oldest LS registry was established in 1992 in Sao Paulo (Brazil), and the youngest this year in San Jose (Costa Rica). In total, 87% (26/30) of the participating centres/registries belonging to the nine countries are performing genetic testing. Overall, 1352 suspected families were sequenced. Pathogenic variants were identified in 34% of the families, with slightly differing distribution of variants between females and males. Path_MLH1 variants were identified in 39% of females and 50% of males (p = 0.023), while path_MSH2 were identified in 37% of females and males, followed by path_PMS2 in 11% of females and 8% of males, path_MSH6 in 13% of females and 3% of males (p < 0.001) and path_EPCAM in 0.3% of females and 2% of males. In Latin America, 9 of 12 (75%) participating countries had implemented healthcare for LS. LS screening is inconsistently applied within Latin America healthcare systems because of structural differences in the healthcare systems between the countries.

Xeroderma Pigmentosum with Severe Neurological Manifestations/De Sanctis-Cacchione Syndrome and a Novel XPC Mutation.

Several genetic disorders caused by defective nucleotide excision repair that affect the skin and the nervous system have been described, including Xeroderma Pigmentosum (XP), De Sanctis-Cacchione syndrome (DSC), Cockayne syndrome, and Trichothiodystrophy. Cutaneous photosensitivity with an increased risk of skin malignancy is a common feature of these disorders, but clinical manifestations commonly overlap these syndromes. Several genes have been found to be altered in these pathologies, but we lack more genotype-phenotype correlations in order to make an accurate diagnosis. Very few cases of DSC syndrome have been reported in the literature. We present a case of a 12-year-old Colombian male, with multiple skin lesions in sun-exposed areas from the age of 3 months and a history of 15 skin cancers. He also displayed severe neurologic abnormalities (intellectual disability, ataxia, altered speech, and hyperreflexia), short stature, and microcephaly, which are features associated with DSC. Genetic testing revealed a novel germline mutation in the XP-C gene (c.547A>T). This is the first case of an XP-C mutation causing De Sanctis-Cacchione syndrome. Multigene panel testing is becoming more widely available and accessible in the clinical setting and will help rapidly unveil the molecular etiology of these rare genetic disorders.

Li-Fraumeni syndrome.

The Li-Fraumeni syndrome is characterized clinically by the appearance of tumors in multiple organs generally at an early age. This hereditary condition is caused by germinal mutations in the TP53 gene, which codifies for the tumoural suppressor gene p53. We present the case of a patient aged 31 with clinical and molecular diagnosis of Li-Fraumeni syndrome who presented two synchronous tumors: a leiomyosarcoma on the forearm and a phyllodes breast tumour. She had a family history of cancer, including a son diagnosed with a cortical adrenal carcinoma when he was three years old, who died at five from the disease. Furthermore, her maternal grandmother and great-grandmother died of stomach cancer at 56 and 60 years old, respectively, while her other great-grandmother and a great aunt presented with breast cancer at the ages of 60 and 40, respectively. After genetic counseling, complete sequencing and analysis of duplications and deletions in the TP53 gene were ordered prior to diagnosis. The molecular analysis of a DNA sample taken from peripheral blood lymphocytes revealed the germinal mutation c.527G>T (p.Cys176Phe) on exon 5 of the TP53 gene, a deleterious mutation described previously in tumoural tissues. To our knowledge, this is the first published case in Colombia of Li-Fraumeni syndrome with confirmed molecular diagnosis. The diagnosis and management of Li-Fraumeni syndrome should be performed by a multidisciplinary team, and genetic counselling should be offered to patients and their relatives.

Síndrome de Li-Fraumeni / Li-Fraumeni syndrome

El síndrome de Li-Fraumeni se caracteriza por la aparición de tumores en múltiples órganos, generalmente a temprana edad. Esta condición hereditaria es causada por mutaciones germinales en el gen TP53 , que codifica el gen supresor tumoral p53 . Se presenta el caso de una paciente de 31 años con diagnóstico clínico y molecular de síndrome de Li-Fraumeni, que presentó dos tumores sincrónicos a los 31 años: un leiomiosarcoma de antebrazo y un tumor filoides de mama. Tenía el antecedente de un hijo con diagnóstico de carcinoma cortical suprarrenal a los tres años, que falleció a los cinco años debido a la enfermedad. Además, su abuela y su bisabuela maternas habían fallecido de cáncer gástrico a los 56 y 60 años, respectivamente, y la madre y una hermana de su abuelo materno presentaron cáncer de mama pasados los 60 y los 40 años de edad, respectivamente. Después de una asesoría genética, se ordenó hacer la secuenciación completa y el análisis de duplicaciones y deleciones en el gen TP53 . El estudio molecular en una muestra de ADN proveniente de linfocitos de sangre periférica reveló la mutación germinal c.527G>T (p.Cys176Phe) en el exón 5 del gen, mutación deletérea descrita anteriormente en tejidos tumorales. Hasta donde se sabe, este es el primer caso que se publica en Colombia de síndrome de Li-Fraumeni con diagnóstico molecular confirmado. El diagnóstico y el manejo del síndrome de Li-Fraumeni deben estar a cargo de un equipo multidisciplinario, y debe contarse con asesoría genética para el paciente y sus familiares.

The Li-Fraumeni syndrome is characterized clinically by the appearance of tumors in multiple organs generally at an early age. This hereditary condition is caused by germinal mutations in the TP53 gene, which codifies for the tumoural suppressor gene p53 . We present the case of a patient aged 31 with clinical and molecular diagnosis of Li-Fraumeni syndrome who presented two synchronous tumors: a leiomyosarcoma on the forearm and a phyllodes breast tumour. She had a family history of cancer, including a son diagnosed with a cortical adrenal carcinoma when he was three years old, who died at five from the disease. Furthermore, her maternal grandmother and great-grandmother died of stomach cancer at 56 and 60 years old, respectively, while her other great-grandmother and a great aunt presented with breast cancer at the ages of 60 and 40, respectively. After genetic counseling, complete sequencing and analysis of duplications and deletions in the TP53 gene were ordered prior to diagnosis. The molecular analysis of a DNA sample taken from peripheral blood lymphocytes revealed the germinal mutation c.527G>T (p.Cys176Phe) on exon 5 of the TP53 gene, a deleterious mutation described previously in tumoural tissues. To our knowledge, this is the first published case in Colombia of Li-Fraumeni syndrome with confirmed molecular diagnosis. The diagnosis and management of Li-Fraumeni syndrome should be performed by a multidisciplinary team, and genetic counselling should be offered to patients and their relatives.